Treatment of urinary incontinence can involve implanting an artificial sphincter in a patient.
Such a sphincter typically comprises an occlusive cuff placed around the urethra (in men or women) or sometimes the bladder neck (in women) or the prostate in men with the aim of exerting direct or indirect compression on the urethra to prevent urinary leaks, an activation device of said cuff to vary compression exerted on the urethra or the bladder neck, as well as a control unit of the activation device.
Such an artificial sphincter is described in particular in [1].
Different technologies of artificial sphincters have been proposed, based in particular on different types of occlusive cuffs and associated activation mode.
According to an embodiment, the occlusive cuff is an inflatable cuff filled with fluid.
The compression device is a hydraulic device, comprising a reservoir of said fluid and an electromechanical actuator for adding or withdrawing said fluid to compress or decompress the part occluding.
Such an artificial sphincter is described for example in [2].
Another example of artificial sphincter is described in [3].
There is also a sphincter based on mechanical operation, wherein the occlusive cuff is a band surrounding the urethra or the bladder neck and connected to a strap which exerts more or less strong mechanical tension on the band by means of an electromechanical actuator [4].
When the patient must undergo an endo-urethral procedure, typically urethral catheterization, wherein, as illustrated in FIG. 1, a probe is introduced into the urethra as far as the bladder and very strong pressure is exerted on the urethra in the region surrounded by the occlusive cuff.
It is therefore recommended that practitioners release pressure exerted by the cuff prior to proceeding with insertion of the instrument or probe and throughout insertion by deactivating the artificial sphincter [5].
In fact, in the absence of such a precaution, this excessive pressure is responsible for the phenomenon of erosion of the urethra by creating a breach in its wall, causing the cuff to partially or totally be in the space of the urethra.
This erosion of the urethra involves surgical intervention to remove the cuff or even the entire artificial sphincter. Once the urethra scars over, requiring several months, a new artificial sphincter can be implanted.
Urethral erosion following an endo-urethral procedure, and quite particularly after placing a probe, is a major cause for revision of the implant.
Of revision cases connected with urethral erosion, over half are due to urethral catheterization occurring while the cuff was compressing the urethra [6].
In this respect, some clinicians estimate that the probe damages the urethra as soon as it passes through the region surrounded by the occlusive cuff; other clinicians however think that erosion occurs when excessive compression is applied beyond a certain period.
In addition, insertion of the probe can cause deterioration of the occlusive cuff and/or of the associated activation device due to the very high pressure generated.
In any case, during an endo-urethral procedure such as catheterization or introduction of a fibroscope for example it is preferable that compression of the urethra is released from insertion of the endo-urethral device and throughout the presence of the latter in the urethra.
In principle, the patient or nursing personnel can control decompression of the cuff by control means provided in the artificial sphincter.
However, there are situations wherein this prior decompression is not possible.
Such is the case for example of surgical intervention performed urgently on a patient, the nursing personnel not necessarily having knowledge of the presence of the implanted artificial sphincter.
To ensure, even in such a situation, that the endo-urethral procedure does not damage the urethra, the aim is to therefore provoke automatic decompression of the cuff during insertion of the device.
However, to prevent accidental urinary leaks, it is necessary for this decompression to be caused only when an endo-urethral device is really introduced into the urethra.
Now, there are situations where pressure exerted on the urethra is very high without a urethral probe having been introduced.
So, when the patient is seated it is possible for him to press strongly on his perineum, causing a rise in compression of the same order as that caused by the introduction of a probe.
A simple measurement of the compression of the urethra therefore fails to reliably detect an endo-urethral procedure.